pip should always install dist-info rather than egg-info when possible

[segevfiner]

• Pip version: 9.0.1
• Python version: 2.7.13
• Operating system: Windows 10.0.15063 x64

Description:

There are certain cases where pip doesn't build a wheel and resorts to setup.py install. In such cases it will create egg-info metadata and install it. I think that it would be nice if pip converts such egg-info to the standardized dist-info metadata, without building a wheel to do so.

Though maybe there are packages that don't work as a wheel and depend on egg-info stuff...

EDIT: I think this gets fixed by #4562, since than pip will always install via a wheel if possible.

What I've run:

# setup.py
from setuptools import setup

setup(
    name="spam",
    version="0.1.0",
    py_modules="spam",
)

pip install .

I get an egg-info in site-packages. While I will get dist-info if I bdist_wheel and install the wheel.

[pradyunsg]

#4562 would fix this by installing from directories using a wheel. Closing this issue in favour of that.